The thermodynamics, heat transer and fluid mechanics role of lubricant oil in hermetic reciprocating compressors

Abstract:

Paper presented at the 5th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 1-4 July, 2007.

The present paper reviews recent developments on the
influence of oil on several thermophysical phenomena in
reciprocating compressors. Besides the more essential role of
lubrication, the oil is responsible for several tasks in the
compressor, from cooling to keeping a low system pressure
while the compressor is idle. Thermodynamics dictates the
amount of dissolved refrigerant the oil can retain at a particular
condition. Hence, the viscosity of the lubricant is directly
affected by the refrigerant solubility in the oil. Heat transfer is
crucial for keeping a low temperature in the compressor
because thermodynamic losses increase with increasing gas
temperature. Fluid mechanics is essential to guarantee that oil is
delivered to the bearings and that lubrication is performed
efficiently under any operating condition.